1. Field of the Invention
The present invention is directed to absorbent nonwoven fabrics useful, for example, for applications such as wipers, protective covers, and the like. In particular, the nonwoven fabrics of the present invention not only demonstrate high absorbency for oils and greases but also have the ability to easily release such materials upon application of moderate pressure as by hand wringing or squeezing. These fabrics will be ideally suited for food service wiper applications as well as for limited use applications such as protective covers for under auto use or to place over auto upholstery during repairs. Nonwoven fabrics of this type are generally made by collecting fibers or filaments into a web and bonding the web before or after treating the fibers or filaments to obtain desired properties. Such fabrics may be used as so formed or may be combined with other fabrics or components in the construction of products for these and various other applications.
2. Description of the Prior Art
It is well-known to form nonwoven webs having a high affinity for oils and greases. Further, it is well-known to form such webs from microfibers for wiper applications. Examples of such wiper products are described in U.S. Pat. No. 4,307,143 to Meitner dated Dec. 22, 1981, U.S. Pat. No. 4,328,279 to Meitner and Englebert dated May 4, 1982, and U.S Pat. No. 4,426,417 to Meitner and Hotchkiss dated Jan. 17, 1984. The last of these patents also describes wiper materials containing microfibers in a mixture with other fiber components including staple synthetic fibers and cotton fibers. While such wipers have been highly useful in absorbing oil and grease for single use applications, many wiper applications require a wiper that can be wrung out and reused over an extended period. In particular, wipers for food service applications such as in restaurants, cafeterias, and the like require that the wiper be capable of being wrung out, rinsed and reused. For these applications conventional microfiber wipers have not been entirely satisfactory since the highly oleophillic nature of the fibers combined with the aggressive structure created by the capillaries tends to hold oil and grease so that it is not easily released upon wringing out or squeezing. In addition, nonwoven fabrics used for protective covers for auto upholstery or under auto use over floors will desirably release oil and grease upon rinsing and wringing out. Similarly oil scavengers for use on oil spills advantageously will release the oil upon squeezing both for purposes of reuse of the scavenger and for recycle of the oil. For these and other applications, it is desired to improve nonwoven fabrics and particularly the ability of such nonwoven fabrics to easily rinse oil and grease.